Indonesia’s Mount Semeru erupted violently this week, propelling volcanic ash over 6,500 feet into the sky and prompting aviation warnings across Southeast Asia.

Authorities raised the volcano’s alert status to Level 4—the highest level—signaling an ongoing eruption. Indonesia’s Disaster Mitigation Agency reported that around 300 residents from nearby villages were evacuated to shelters.

Australia’s Bureau of Meteorology issued a Volcanic Ash Advisory, warning that the eruption poses an immediate threat to regional air traffic. The Indonesian government has banned entry within a 12-mile radius of the volcano due to risks from hot ash clouds and potential lava flows.

Officials released images showing volcanic ash surrounding infrastructure just 8 miles from the summit. Pyroclastic rocks may be ejected up to 5 miles from the peak, according to government warnings.

Mount Semeru, a stratovolcano standing over 5,500 feet above sea level, is the tallest volcano on Java and among the most active in the region. Its latest eruption occurred on November 6.